/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date:        19. March 2015
* $Revision: 	V.1.4.5
*
* Project: 	    CMSIS DSP Library
* Title:	    arm_fir_sparse_q15.c
*
* Description:	Q15 sparse FIR filter processing function.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* POSSIBILITY OF SUCH DAMAGE.
* ------------------------------------------------------------------- */
#include "arm_math.h"

/**
 * @addtogroup FIR_Sparse
 * @{
 */

/**
 * @brief Processing function for the Q15 sparse FIR filter.
 * @param[in]  *S           points to an instance of the Q15 sparse FIR structure.
 * @param[in]  *pSrc        points to the block of input data.
 * @param[out] *pDst        points to the block of output data
 * @param[in]  *pScratchIn  points to a temporary buffer of size blockSize.
 * @param[in]  *pScratchOut points to a temporary buffer of size blockSize.
 * @param[in]  blockSize    number of input samples to process per call.
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function is implemented using an internal 32-bit accumulator.
 * The 1.15 x 1.15 multiplications yield a 2.30 result and these are added to a 2.30 accumulator.
 * Thus the full precision of the multiplications is maintained but there is only a single guard bit in the accumulator.
 * If the accumulator result overflows it will wrap around rather than saturate.
 * After all multiply-accumulates are performed, the 2.30 accumulator is truncated to 2.15 format and then saturated to 1.15 format.
 * In order to avoid overflows the input signal or coefficients must be scaled down by log2(numTaps) bits.
 */


void arm_fir_sparse_q15(
    arm_fir_sparse_instance_q15 *S,
    q15_t *pSrc,
    q15_t *pDst,
    q15_t *pScratchIn,
    q31_t *pScratchOut,
    uint32_t blockSize)
{

    q15_t *pState = S->pState;                     /* State pointer */
    q15_t *pIn = pSrc;                             /* Working pointer for input */
    q15_t *pOut = pDst;                            /* Working pointer for output */
    q15_t *pCoeffs = S->pCoeffs;                   /* Coefficient pointer */
    q15_t *px;                                     /* Temporary pointers for scratch buffer */
    q15_t *pb = pScratchIn;                        /* Temporary pointers for scratch buffer */
    q15_t *py = pState;                            /* Temporary pointers for state buffer */
    int32_t *pTapDelay = S->pTapDelay;             /* Pointer to the array containing offset of the non-zero tap values. */
    uint32_t delaySize = S->maxDelay + blockSize;  /* state length */
    uint16_t numTaps = S->numTaps;                 /* Filter order */
    int32_t readIndex;                             /* Read index of the state buffer */
    uint32_t tapCnt, blkCnt;                       /* loop counters */
    q15_t coeff = *pCoeffs++;                      /* Read the first coefficient value */
    q31_t *pScr2 = pScratchOut;                    /* Working pointer for pScratchOut */


#ifndef ARM_MATH_CM0_FAMILY

    /* Run the below code for Cortex-M4 and Cortex-M3 */

    q31_t in1, in2;                                /* Temporary variables */


    /* BlockSize of Input samples are copied into the state buffer */
    /* StateIndex points to the starting position to write in the state buffer */
    arm_circularWrite_q15(py, delaySize, &S->stateIndex, 1, pIn, 1, blockSize);

    /* Loop over the number of taps. */
    tapCnt = numTaps;

    /* Read Index, from where the state buffer should be read, is calculated. */
    readIndex = (S->stateIndex - blockSize) - *pTapDelay++;

    /* Wraparound of readIndex */
    if(readIndex < 0)
    {
        readIndex += (int32_t) delaySize;
    }

    /* Working pointer for state buffer is updated */
    py = pState;

    /* blockSize samples are read from the state buffer */
    arm_circularRead_q15(py, delaySize, &readIndex, 1,
                         pb, pb, blockSize, 1, blockSize);

    /* Working pointer for the scratch buffer of state values */
    px = pb;

    /* Working pointer for scratch buffer of output values */
    pScratchOut = pScr2;

    /* Loop over the blockSize. Unroll by a factor of 4.
     * Compute 4 multiplications at a time. */
    blkCnt = blockSize >> 2;

    while(blkCnt > 0u)
    {
        /* Perform multiplication and store in the scratch buffer */
        *pScratchOut++ = ((q31_t) * px++ * coeff);
        *pScratchOut++ = ((q31_t) * px++ * coeff);
        *pScratchOut++ = ((q31_t) * px++ * coeff);
        *pScratchOut++ = ((q31_t) * px++ * coeff);

        /* Decrement the loop counter */
        blkCnt--;
    }

    /* If the blockSize is not a multiple of 4,
     * compute the remaining samples */
    blkCnt = blockSize % 0x4u;

    while(blkCnt > 0u)
    {
        /* Perform multiplication and store in the scratch buffer */
        *pScratchOut++ = ((q31_t) * px++ * coeff);

        /* Decrement the loop counter */
        blkCnt--;
    }

    /* Load the coefficient value and
     * increment the coefficient buffer for the next set of state values */
    coeff = *pCoeffs++;

    /* Read Index, from where the state buffer should be read, is calculated. */
    readIndex = (S->stateIndex - blockSize) - *pTapDelay++;

    /* Wraparound of readIndex */
    if(readIndex < 0)
    {
        readIndex += (int32_t) delaySize;
    }

    /* Loop over the number of taps. */
    tapCnt = (uint32_t) numTaps - 2u;

    while(tapCnt > 0u)
    {
        /* Working pointer for state buffer is updated */
        py = pState;

        /* blockSize samples are read from the state buffer */
        arm_circularRead_q15(py, delaySize, &readIndex, 1,
                             pb, pb, blockSize, 1, blockSize);

        /* Working pointer for the scratch buffer of state values */
        px = pb;

        /* Working pointer for scratch buffer of output values */
        pScratchOut = pScr2;

        /* Loop over the blockSize. Unroll by a factor of 4.
         * Compute 4 MACS at a time. */
        blkCnt = blockSize >> 2;

        while(blkCnt > 0u)
        {
            /* Perform Multiply-Accumulate */
            *pScratchOut++ += (q31_t) * px++ * coeff;
            *pScratchOut++ += (q31_t) * px++ * coeff;
            *pScratchOut++ += (q31_t) * px++ * coeff;
            *pScratchOut++ += (q31_t) * px++ * coeff;

            /* Decrement the loop counter */
            blkCnt--;
        }

        /* If the blockSize is not a multiple of 4,
         * compute the remaining samples */
        blkCnt = blockSize % 0x4u;

        while(blkCnt > 0u)
        {
            /* Perform Multiply-Accumulate */
            *pScratchOut++ += (q31_t) * px++ * coeff;

            /* Decrement the loop counter */
            blkCnt--;
        }

        /* Load the coefficient value and
         * increment the coefficient buffer for the next set of state values */
        coeff = *pCoeffs++;

        /* Read Index, from where the state buffer should be read, is calculated. */
        readIndex = (S->stateIndex - blockSize) - *pTapDelay++;

        /* Wraparound of readIndex */
        if(readIndex < 0)
        {
            readIndex += (int32_t) delaySize;
        }

        /* Decrement the tap loop counter */
        tapCnt--;
    }

    /* Compute last tap without the final read of pTapDelay */

    /* Working pointer for state buffer is updated */
    py = pState;

    /* blockSize samples are read from the state buffer */
    arm_circularRead_q15(py, delaySize, &readIndex, 1,
                         pb, pb, blockSize, 1, blockSize);

    /* Working pointer for the scratch buffer of state values */
    px = pb;

    /* Working pointer for scratch buffer of output values */
    pScratchOut = pScr2;

    /* Loop over the blockSize. Unroll by a factor of 4.
     * Compute 4 MACS at a time. */
    blkCnt = blockSize >> 2;

    while(blkCnt > 0u)
    {
        /* Perform Multiply-Accumulate */
        *pScratchOut++ += (q31_t) * px++ * coeff;
        *pScratchOut++ += (q31_t) * px++ * coeff;
        *pScratchOut++ += (q31_t) * px++ * coeff;
        *pScratchOut++ += (q31_t) * px++ * coeff;

        /* Decrement the loop counter */
        blkCnt--;
    }

    /* If the blockSize is not a multiple of 4,
     * compute the remaining samples */
    blkCnt = blockSize % 0x4u;

    while(blkCnt > 0u)
    {
        /* Perform Multiply-Accumulate */
        *pScratchOut++ += (q31_t) * px++ * coeff;

        /* Decrement the loop counter */
        blkCnt--;
    }

    /* All the output values are in pScratchOut buffer.
       Convert them into 1.15 format, saturate and store in the destination buffer. */
    /* Loop over the blockSize. */
    blkCnt = blockSize >> 2;

    while(blkCnt > 0u)
    {
        in1 = *pScr2++;
        in2 = *pScr2++;

#ifndef  ARM_MATH_BIG_ENDIAN

        *__SIMD32(pOut)++ =
            __PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16),
                    16);

#else
        *__SIMD32(pOut)++ =
            __PKHBT((q15_t) __SSAT(in2 >> 15, 16), (q15_t) __SSAT(in1 >> 15, 16),
                    16);

#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */

        in1 = *pScr2++;

        in2 = *pScr2++;

#ifndef  ARM_MATH_BIG_ENDIAN

        *__SIMD32(pOut)++ =
            __PKHBT((q15_t) __SSAT(in1 >> 15, 16), (q15_t) __SSAT(in2 >> 15, 16),
                    16);

#else

        *__SIMD32(pOut)++ =
            __PKHBT((q15_t) __SSAT(in2 >> 15, 16), (q15_t) __SSAT(in1 >> 15, 16),
                    16);

#endif /*      #ifndef  ARM_MATH_BIG_ENDIAN    */


        blkCnt--;

    }

    /* If the blockSize is not a multiple of 4,
       remaining samples are processed in the below loop */
    blkCnt = blockSize % 0x4u;

    while(blkCnt > 0u)
    {
        *pOut++ = (q15_t) __SSAT(*pScr2++ >> 15, 16);
        blkCnt--;
    }

#else

    /* Run the below code for Cortex-M0 */

    /* BlockSize of Input samples are copied into the state buffer */
    /* StateIndex points to the starting position to write in the state buffer */
    arm_circularWrite_q15(py, delaySize, &S->stateIndex, 1, pIn, 1, blockSize);

    /* Loop over the number of taps. */
    tapCnt = numTaps;

    /* Read Index, from where the state buffer should be read, is calculated. */
    readIndex = (S->stateIndex - blockSize) - *pTapDelay++;

    /* Wraparound of readIndex */
    if(readIndex < 0)
    {
        readIndex += (int32_t) delaySize;
    }

    /* Working pointer for state buffer is updated */
    py = pState;

    /* blockSize samples are read from the state buffer */
    arm_circularRead_q15(py, delaySize, &readIndex, 1,
                         pb, pb, blockSize, 1, blockSize);

    /* Working pointer for the scratch buffer of state values */
    px = pb;

    /* Working pointer for scratch buffer of output values */
    pScratchOut = pScr2;

    blkCnt = blockSize;

    while(blkCnt > 0u)
    {
        /* Perform multiplication and store in the scratch buffer */
        *pScratchOut++ = ((q31_t) * px++ * coeff);

        /* Decrement the loop counter */
        blkCnt--;
    }

    /* Load the coefficient value and
     * increment the coefficient buffer for the next set of state values */
    coeff = *pCoeffs++;

    /* Read Index, from where the state buffer should be read, is calculated. */
    readIndex = (S->stateIndex - blockSize) - *pTapDelay++;

    /* Wraparound of readIndex */
    if(readIndex < 0)
    {
        readIndex += (int32_t) delaySize;
    }

    /* Loop over the number of taps. */
    tapCnt = (uint32_t) numTaps - 2u;

    while(tapCnt > 0u)
    {
        /* Working pointer for state buffer is updated */
        py = pState;

        /* blockSize samples are read from the state buffer */
        arm_circularRead_q15(py, delaySize, &readIndex, 1,
                             pb, pb, blockSize, 1, blockSize);

        /* Working pointer for the scratch buffer of state values */
        px = pb;

        /* Working pointer for scratch buffer of output values */
        pScratchOut = pScr2;

        blkCnt = blockSize;

        while(blkCnt > 0u)
        {
            /* Perform Multiply-Accumulate */
            *pScratchOut++ += (q31_t) * px++ * coeff;

            /* Decrement the loop counter */
            blkCnt--;
        }

        /* Load the coefficient value and
         * increment the coefficient buffer for the next set of state values */
        coeff = *pCoeffs++;

        /* Read Index, from where the state buffer should be read, is calculated. */
        readIndex = (S->stateIndex - blockSize) - *pTapDelay++;

        /* Wraparound of readIndex */
        if(readIndex < 0)
        {
            readIndex += (int32_t) delaySize;
        }

        /* Decrement the tap loop counter */
        tapCnt--;
    }

    /* Compute last tap without the final read of pTapDelay */

    /* Working pointer for state buffer is updated */
    py = pState;

    /* blockSize samples are read from the state buffer */
    arm_circularRead_q15(py, delaySize, &readIndex, 1,
                         pb, pb, blockSize, 1, blockSize);

    /* Working pointer for the scratch buffer of state values */
    px = pb;

    /* Working pointer for scratch buffer of output values */
    pScratchOut = pScr2;

    blkCnt = blockSize;

    while(blkCnt > 0u)
    {
        /* Perform Multiply-Accumulate */
        *pScratchOut++ += (q31_t) * px++ * coeff;

        /* Decrement the loop counter */
        blkCnt--;
    }

    /* All the output values are in pScratchOut buffer.
       Convert them into 1.15 format, saturate and store in the destination buffer. */
    /* Loop over the blockSize. */
    blkCnt = blockSize;

    while(blkCnt > 0u)
    {
        *pOut++ = (q15_t) __SSAT(*pScr2++ >> 15, 16);
        blkCnt--;
    }

#endif /*   #ifndef ARM_MATH_CM0_FAMILY */

}

/**
 * @} end of FIR_Sparse group
 */
